I was pretty busy since August 2024 with a lot of other tasks, mostly job-related and did not have too much time for DIY and tinkering. And this included my SA818 project.
Fan control with dtoverlay on Raspberry
Another day working a bit for my SA818 radio node project. Today I tried active cooling with a 5V fan driven from RPIs 5V rail and controlled from GPIOs with a MOSFET (2N7002).
Adalm Pluto ? Don’t think so
I have a love-hate relationship with Adalm Pluto. I bought it from Mouser in 2020 when it was roughly 100 euros (now it is almost double that price !) and I never managed to do anything useful with it.
Raspberry Pi serial interface issues
There is a problem I forgot to take care before creating the custom image for my radio node project. Programming SA818 module via Raspberry Pi’s UART interface cannot be done unless the UART interface is released from any interaction in console mode. I was banging my head for hours because of sustained DMOERROR message for […]
I am learning morse
I was always interested in learning morse but I did not have my mind seriously set on it until recently. My shack conditions do not allow me do much DX-ing on SSB and I am not very keen of FT8 and other digital modes so I consider CW as the only possible way to get […]
How to write to CM108 GPIO from Svxlink
CM108 has a set of four GPIOs that can be used via hidraw. These can be read from or write to.
Flir C2 thermal imaging of SA818 radio node
Today I did some thermal measurements with my Flir C2.
Raspberry Pi compatible, SA818 radio node
My new radio node that I designed last month is back from production at jlcpcb. Designed in Romania and built in China 😁. This is my first attempt using jlcpcb for the entire manufacturing chain, from PCB creation to part selection and assembly.
New radio node
Today I finalzied the designed for my new Raspberry Pi Zero-based radio node. Designed around SA818 and CM108B sound codec, will replace my old dead-bug style radio node that I used for so many years.
I2S Raspberry Interface (4)
More work today. Some wires got loose and I did some experiments with .asoundrc and ALSA settings. I added a 39 Ω ballast resistor on SDIN and SDOUT lines and put a ferrite core on both wires. The radio node works as expected, absolutely no issues with one exception, a periodic pop that is audible […]
I2S Raspberry Interface (3)
Update July 11, 2025 Some thoughts and tasks today. The project is the same I2S interface.
A Si5351 DIY oscillator project
I have some Si5351 chips that I never used for any projects. I purchased them from Mouser, I believe for an APRS project, long-standing and overdue. That APRS project I started some time ago but I never completed and maybe I should strongly consider to complete. But this is another topic.
Significant Svxlink power consumption
While testing my I2S project I ran into some boot issues on the Raspberry Pi 4 host. For what seemed to be some unknown reasons the boot process was completely chaotic, sometimes running well, sometimes hanging. I banged my head for some time looking for a solution until it came to my mind to change […]
AT1846S QFN 32 — Did I solder it correctly ?
RDA1846, the transceiver inside Baofeng UV-5R, Yaesu FT-4XR, SA818 and other radios is no longer manufactured. There are equivalent chips that can be used.
I2S Raspberry Interface (2)
Update September, 2024. Activities and notes while developing the I2S interface for my radio node.
I2S interface for Raspberry Pi (1)
Today I managed to connect the Digilent Pmod I2S2 to a Raspberry Pi 4 and have all frequencies generated. This is part of an older project that I left abandoned for a while: a radio node built on Raspberry Pi and using Svxlink. As known, Raspberry boards do not have a proper audio interface and […]
Controller for DR-1X repeater
I made this for a friend. Is a remote controller for Yaesu DR-1X repetear that is installed on Summit Heniu (145.725 Tx -6khz Rx). This is a mixed digital (C4FM) and analogue repeater that is covering almost all northern half of Transyvania and can also be accessed via Echolink YO5D-R, node 54452. This version is […]
Harris 300W UHF Pallet
A couple of days ago I received from a friend of mine a Harris RF power pallet salvaged from a scrapped equipment. This pallet would be able to dissipate apx 300W PEP (black) on a 50 ohm load on ∼800 Mhz. Unfortunately I have no documentation for this. I do have the schematic but is […]
Malamute SDR
I have to confess that I fail to comprehend this obsession for cheap chinese devices. Although I understand the “cheap” part of the rationale, what constantly amaze me is the fact that usually people that buy such stuff are not necessarily financially challenged — a fact that could justify such a choice. Let’s be honest: […]
Cold shrink tubes
I discovered this technology rather recently on YouTube and I was instantly hooked by the opportunities. I bet most of you who had to insulate connectors or sections of hardware (like antenna segments, for example) relied heavily either on self vulcanizing tape or on electrical insulation tape. Both had disadvantages but for me the deal […]
Multipurpose RF Proto Board v2.0
This is a general purpose PCB that I designed in KiCad as a helper board for my Manhattan-style mounted RF projects. It allows connection via SMA connector (vertical or edge mount) and BNC. The two completely separated prototyping sections can be interconnected by using the SMAs in the middle or, if you want to save […]
Motor drivers for antenna rotator
I made some progress on my antenna rotator project and installed the stepper drivers and the Raspberry Pi computer. I bought two drivers from ardushop.ro and these should work just fine. They are based on Toshiba TB6560AHQ, PWM Chopper-Type Bipolar Driver IC for Stepping Motor Control. The datasheet can be downloaded from here. My projects […]
Mini N connector – timelapse in Fusion360
I needed this 3D design for a mini N connector that I have in my shack but I was unable to find any 3d file (.STEP etc) online. The connectors are used for my 101dB attenuator project. Enjoy ! Greetings.
Project status – 3D printed antenna rotator (16/09/2021)
My 3D printed antenna rotator project for ham radio satellites. Status 09/16/2021
Build SvxLink on Orange Pi — aide-mémoire
This is mostly a memory helper, to remind me some steps in the setup of Svxlink on Orange Pi Load packages sudo apt update sudo apt install g++ cmake make libsigc++-2.0-dev libgsm1-dev libpopt-dev tcl8.5-dev libgcrypt20-dev libspeex-dev libasound2-dev libopus-dev librtlsdr-dev doxygen groff alsa-utils vorbis-tools curl libcurl4-openssl-dev git rtl-sdr libcurl4-openssl-dev Create svxlink user and add to groups […]
Build SvxLink on Raspberry — aide-mémoire
This is not really a post, but mostly a reminder with some information to help me remember the steps. Meanwhile I wrote a much more extensive documentation here, on my wiki (in romanian). And I think I also made a video tutorial but I have to upload it to YouTube. Load packages sudo apt update […]
First steps with Orange Pi
This is rather a reminder, not a real post. This is a collection of links to help me in my quest to control this device.
KiCad Templates for Orange Pi Zero
KiCad templates for two different hat models for Orange Pi Zero boards can be downloaded from my GitHub repo. Two different KiCad templates can be downloaded in the same GitHub archive: one uncut, 46×48 mm exactly same size as Orange Pi Zero; the other one has some cuts for network and USB connector, to accomodate […]
Kenwood THD74 measurements
Some RF power masurements done with my Rigol DS 815TG of my Kenwood THD74.
AD8307 RF Power Meter III — build
This will be another short post. I also made the GitHub repo public, but please be aware, current design is flawed. If you use it, you acknowledge that you use it on your own risk. Today I managed to build the revision 1.0 of this power sensor, not without some lessons learned. It was my […]